/in/foo.cc: In function 'int main()':
/in/foo.cc:72:8: warning: 'b2' may be used uninitialized in this function [-Wmaybe-uninitialized]
   a=crt(a1,w1,b2,w2),b=crt(b1,w1,a2,w2);
     ~~~^~~~~~~~~~~~~
/in/foo.cc:61:10: warning: 'a2' may be used uninitialized in this function [-Wmaybe-uninitialized]
  ll a=crt(a1,w1,a2,w2),b=crt(b1,w1,b2,w2);
       ~~~^~~~~~~~~~~~~
/in/foo.cc:61:29: warning: 'b1' may be used uninitialized in this function [-Wmaybe-uninitialized]
  ll a=crt(a1,w1,a2,w2),b=crt(b1,w1,b2,w2);
                          ~~~^~~~~~~~~~~~~
/in/foo.cc:72:8: warning: 'a1' may be used uninitialized in this function [-Wmaybe-uninitialized]
   a=crt(a1,w1,b2,w2),b=crt(b1,w1,a2,w2);
     ~~~^~~~~~~~~~~~~